Sikaiana is a disputed Polynesian atoll located in the Pacific Ocean and Oceania. The mostly inaccessible atoll, populated with about 300 Polynesian inhabitants, is disputed between New Guinea and Hawaii. New Guinea claims the atoll as a tribal reserve, while Hawaii claims it as a territory. Sikaiana is also a self-declared state, although its sovereignty remains unrecognized by any country.

Hawaii's claim to the atoll originates from 1856, when the residents of Sikaiana ceded their sovereignty to Hawaii. Even when the Privy Council and King Kamehameha IV approved the cession, it was never finalized since the great distance from the Hawaiian islands to Sikaiana would make governing the atoll impossible.

New Guinea claims the atoll because based on treaties regarding national waters, Sikaiana falls well within New Guinean waters. Since Hawaii was unable to formalize the cession of Sikaiana in 1856, New Guinea claims that Sikaiana is indeed not Hawaiian.

Some inhabitants of Sikaiana wish for the atoll to become a sovereign state. It remains largely de facto under control of the inhabitants of Sikaiana, due to the isolation and inaccessibility of the atoll. Unfortunately, this isolation and inaccessibility also means there is a large lack of communication, making it difficult to even establish diplomatic relations; this is one of the main factors in Sikaiana's lack of recognition from the international community.